An active drag-reduction system has first 22 and second 24 fluid outlets located on a vehicle 10 adjacent to a low pressure (drag) region 12, wherein fluid ejected from the second fluid outlet 24 is at a higher pressure/ejection velocity than from the first fluid outlet 22. Turbulent and/or low pressure regions adjacent to vehicles are not uniform, but rather have a varying intensity. For instance, the centre of a region may have a lower pressure and/or more turbulent nature than the periphery of the region. The system injects relatively higher pressure air or relatively higher speed air into the relatively lower pressure/more turbulent part of the low pressure/turbulent region, and relatively lower pressure air or relatively lower speed air into the relatively higher pressure/less turbulent part of the low pressure/turbulent region, compared to each other.

An apparatus including a controllable fluid-contacting surface is provided. In another aspect, the present apparatus includes a flexible membrane and multiple actuators each having an output shaft or activation member coupled to a water-contacting membrane, with the shafts extending in a direction offset from the nominal outer surface of the membrane. A further aspect of the present apparatus includes an underwater vessel including a propulsion source, a flexible membrane having a water-contacting outer surface and an electronic controller including programmable software for actuating the actuators.

An apparatus including a controllable fluid-contacting surface is provided. In another aspect, the present apparatus includes a flexible membrane and multiple actuators each having an output shaft or activation member coupled to a water-contacting membrane, with the shafts extending in a direction offset from the nominal outer surface of the membrane. A further aspect of the present apparatus includes an underwater vessel including a propulsion source, a flexible membrane having a water-contacting outer surface and an electronic controller including programmable software for actuating the actuators.

The present disclosure presents systems, apparatuses, and methods of active flow controls for dissipating tip vortices. In this regard, a method comprises positioning one or more fan-shaped plasma actuators on an end surface of a tip of one or more airfoils of an aircraft, wherein the fan-shaped plasma actuators are surface compliant with the surface of the tip of the one or more airfoils; and activating the one or more fan-shaped plasma actuators during a flight of the aircraft, wherein at least one tip vortex generated by a flight of the aircraft is reduced by an introduction of one or more vortices generated by the one or more fan-shaped plasma actuators on the end surface of the tip of the one or more airfoils of the aircraft. Other systems, apparatuses, and methods are also presented.

The present disclosure presents systems, apparatuses, and methods of active flow controls for dissipating tip vortices. In this regard, a method comprises positioning one or more fan-shaped plasma actuators on an end surface of a tip of one or more airfoils of an aircraft, wherein the fan-shaped plasma actuators are surface compliant with the surface of the tip of the one or more airfoils; and activating the one or more fan-shaped plasma actuators during a flight of the aircraft, wherein at least one tip vortex generated by a flight of the aircraft is reduced by an introduction of one or more vortices generated by the one or more fan-shaped plasma actuators on the end surface of the tip of the one or more airfoils of the aircraft. Other systems, apparatuses, and methods are also presented.

Systems and method for active control of stationary vortices for aerodynamic structures are disclosed herein. In one embodiment, a method for active control of vortices over a solid surface includes: generating vortices proximate to the solid surface; sensing locations of vortices by printed skin sensors; and maintaining the vortices in their fixed spanwise positions with respect to the solid surface by actuation of printed skin actuators.

Systems and method for active control of stationary vortices for aerodynamic structures are disclosed herein. In one embodiment, a method for active control of vortices over a solid surface includes: generating vortices proximate to the solid surface; sensing locations of vortices by printed skin sensors; and maintaining the vortices in their fixed spanwise positions with respect to the solid surface by actuation of printed skin actuators.

An active drag-reduction system has first 22 and second 24 fluid outlets located on a vehicle 10 adjacent to a low pressure (drag) region 12, wherein fluid ejected from the second fluid outlet 24 is at a higher pressure/ejection velocity than from the first fluid outlet 22. Turbulent and/or low pressure regions adjacent to vehicles are not uniform, but rather have a varying intensity. For instance, the centre of a region may have a lower pressure and/or more turbulent nature than the periphery of the region. The system injects relatively higher pressure air or relatively higher speed air into the relatively lower pressure/more turbulent part of the low pressure/turbulent region, and relatively lower pressure air or relatively lower speed air into the relatively higher pressure/less turbulent part of the low pressure/turbulent region, compared to each other.

The present invention is directed to three dimensional (3D) woven lattices for drag and turbulence reduction. 3D woven lattice material can serve as a surface layer that regularizes the flow around a bluff body with beneficial effects on: 1) drag reduction, 2) decrease in turbulence intensity, 3) attenuation of flow-induced vibrations, and 4) aerodynamic noise cancellation. 3-D woven lattice architectures allows for passive flow control (without the need for external energy supply) around bluff bodies with restricted geometry/shape due to their functional requirements such as wind turbine towers, cargo trucks, train cars, etc. The woven material can be easily shaped to fit on various geometries and incorporated in existing manufacturing processes (from composites to metallic plates). Metallic foam and randomly porous materials have been identified in the literature as a promising solution for passive flow control over bluff bodies.

The present invention is directed to three dimensional (3D) woven lattices for drag and turbulence reduction. 3D woven lattice material can serve as a surface layer that regularizes the flow around a bluff body with beneficial effects on: 1) drag reduction, 2) decrease in turbulence intensity, 3) attenuation of flow-induced vibrations, and 4) aerodynamic noise cancellation. 3-D woven lattice architectures allows for passive flow control (without the need for external energy supply) around bluff bodies with restricted geometry/shape due to their functional requirements such as wind turbine towers, cargo trucks, train cars, etc. The woven material can be easily shaped to fit on various geometries and incorporated in existing manufacturing processes (from composites to metallic plates). Metallic foam and randomly porous materials have been identified in the literature as a promising solution for passive flow control over bluff bodies.